The mobile communication system has evolved into a high-speed, high-quality wireless packet data communication system to provide data and multimedia services beyond the early voice-oriented services. Recently, various mobile communication standards, such as High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), Long Term Evolution (LTE), and LTE-Advanced (LTE-A) defined in 3rd Generation Partnership Project (3GPP), High Rate Packet Data (HRPD) defined in 3rd Generation Partnership Project-2 (3GPP2), and 802.16 defined in IEEE, have been developed to support the high-speed, high-quality wireless packet data communication services.
The existing 3rd and 4th generation wireless packet data communication systems (such as HSDPA, HSUPA, HRPD, and LTE/LTE-A) adopt Adaptive Modulation and Coding (AMC) and Channel-Sensitive Scheduling techniques to improve the transmission efficiency. AMC allows the transmitter to adjust the data amount to be transmitted according to the channel condition. That is, the transmitter is capable of decreasing the data transmission amount for bad channel condition so as to fix the received signal error probability at a certain level or increasing the data transmission amount for good channel condition so as to transmit large amount of information efficiently while maintaining the received signal error probability at an intended level. Meanwhile, the channel sensitive scheduling allows the transmitter to serve the user having good channel condition selectively among a plurality of users so as to increase the system capacity as compared to allocating a channel fixedly to serve a single user. This increase in system capacity is referred to as multi-user diversity gain. Both the AMC and channel sensitive scheduling are the method of adopting the best modulation and coding scheme at the most efficient time based on the partial channel state information feedback from the receiver.
Recently, many researches are being conducted to replace Code Division Multiple Access (CDMA) used in the legacy 2nd and 3rd mobile communication systems with Orthogonal Frequency Division Multiple Access (OFDMA) for the next generation mobile communication system. The 3GPP and 3GPP2 are in the middle of the standardization of OFDMA-based evolved system. OFDMA is expected to provide superior system throughput as compared to the CDMA. One of the main factors that allow OFDMA to increase system throughput is the frequency domain scheduling capability. As channel sensitive scheduling increases the system capacity using the time-varying channel characteristic, OFDM can be used to obtain more capacity gain using the frequency-varying channel characteristic.
Meanwhile, the conventional mobile communication terminal transmits a signal such as channel measurement information to the base station periodically. Such periodic signal transmission causes a frequency in a specific bandwidth which corresponds to a reciprocal of the period and the frequency is likely to incur interference on the frequency band for wired or wireless telephony.
Therefore, it is necessary for the terminal to prevent the signal transmitted periodically from causing noise to voice signal of the wired or wireless terminal.